The present invention is related to a shank retaining base for a screwdriver, comprising a handle, a shank body, and a base mount wherein the base mount has a journal section with a roller bead embedded at the upper section and a flexible means covering the outer side thereof which are adapted at a central receiving cavity of the handle therein and protected from outside impact, facilitating the precise retaining of the shank body at the base mount thereof without spinning therein or coming off there-from. Besides, via a circular guide facet and equidistant retaining ribs with oblique guide edges disposed at one side of the journal section thereof, the base mount is straightly guided and smoothly pushed with pressure to the receiving cavity therein, preventing the bottom side of the handle from getting cracked or broken up in assembly. The retaining ribs thereof are securely locked at the receiving cavity therein, refraining the base mount from spinning or coming off from the handle in case of relatively great torque applied onto the shank body.
Please refer to FIG. 1. A conventional shank retaining base for a screwdriver is mainly made up of a handle 10, a base mount 20, and a shank body 30 wherein the handle 10 has a central receiving groove 11 for the base mount 20 to be sleeve joined therein. The base mount 20 has a polygonal sleeve hole 21 disposed at one end matching to the shank body 30 thereof, a round pivot hole 22 disposed at the other end thereof, and a journal section 23 disposed at the outer periphery of one side thereof. The journal section 23 is equipped with a roller bead 231 embedded at the upper side thereof communicating with the polygonal sleeve hole 21 thereof, and a flexible means 232 covering the outer side thereof and matching to the roller bead 231  for location thereof A polygonal coupling section 24 is axially extended at one side of the journal section 23 thereof. The shank body 30 is provided with tool heads 31, 32 of different sizes at both ends thereof.
Please refer to FIG. 2. In assembly, the polygonal coupling section 24 of the base mount 20 is pushed with pressure into the central receiving groove 11 of the handle 10 thereof to join the base mount 20 at the handle 10 therein for a certain length. One end of the shank body 30 with either tool head 31, or 30 of is guided via the roller bead 231 to be sleeve joined to the polygonal sleeve hole 21 and flexibly abutted therein via the roller bead 231 thereof.
There are some drawbacks to such conventional shank retaining base for a screwdriver. First, the roller bead 231 and the flexible means 232 exposed outside the handle 10 can easily get loosened due to impact from outside as shown by the arrow in FIG. 2, failing to retain the shank body 30 securely at the base mount 20 therein. Thus, the shank body 30 can easily spin at the base mount 20 therein or even come off there-from as shown in the double arrow of FIG. 2. Second, the polygonal coupling section 24 of the base mount 20 with a flat bottom end without any guide means disposed thereon can easily get deviated and slantingly joined to the handle 10 as shown in FIG. 3. Besides, cracks A are easily produced at the outer periphery of the central receiving groove 11 thereof when the polygonal coupling section 24 of the base mount 20 is flatly pushed with pressure and joined to the handle 10 as shown in FIG. 4. Third, the polygonal coupling section 24 with smooth multi-facets at the outer periphery thereof is hard to lock the base mount 20 at the handle 10 therein. In case of relatively great torque applied onto the shank body 30, the base mount 20 can easily spin at the handle 10 therein, or even come off there-from. 